#include <stdio.h>

int my_sum(int n){
	int sum = 0;
	int i = 1;
	for(i = 1; i <= n; i++){
		sum += i;
	}
	return sum;
}

int main(int argc, const char *argv[])
{
	int ret = my_sum(10);
	printf("%d\n", ret); // 55

	printf("%d\n", my_sum(100)); // 5050

	return 0;
}
